Life-cycle assessment is being applied to an increasing number of building projects from one side while the usual dynamic thermal simulations are being conducted from the other side on the same projects. However, there are few observations in the literature linking these two types of calculations: embodied and operating energies are rarely directly compared. This paper compares those energies for some case studies. The challenge is to quantify to what extent chosen structural materials can change their global life-cycle energy balance. This question is raised by the different dynamic thermal behavior of materials. Consequently, the case studies focus on the influence of materials’ thermal mass on the operating energy consumptions.Nonetheless, few software programs can conduct both these calculations (LCA and dynamic thermal modeling). The Swiss regulatory tool LESOSAI has been implemented and offers now these two possibilities. However, its LCA database is arcane, this paper will first assess the LCA results of LESOSAI by comparing it with the French tool ELODIE developed by the CSTB. Measuring the reproducibility of their results provides boundaries to the LCA calculations that LESOSAI can perform. These identified limits enable to set the starting assumptions of the case studies. Two raw materials are compared: wood and concrete structures. Considering thermal mass as a dynamic property, different typologies of building usages and climates have been investigated for the materials comparisons. Finally, the conclusion emphasizes the material that permits the lowest life-cycle impact for each typology and climate.